Nickel nanoparticles on nitrogen-doped diamond-like carbon thin films: Variation in nucleation density with deposition potential

Nickel nanoparticles were electro-deposited on nitrogen-doped diamond-like carbon (N-DLC) thin film surface at potentials ranging from -1.1 to -1.4 V versus Ag/AgCl in 0.1 M Na₂SO₄ aqueous solution containing 4 mM NiCl₂. Atomic force microscopy was used to investigate the growth of the nanoparticles. The mean growth rate of the nanoparticles increased, whereas the nucleation density decreased with more negative deposition potential. At more negative potentials, large nanoparticles were obtained. The growth kinetics was studied by the dependence of potentiostatic current density on the deposition time, and the growth mechanism was explained by the cyclic voltammogram of the N-DLC film electrode in the deposition solution. The non-uniform size (height, area, and volume) of the nanoparticles would be attributed to the progressive nucleation and growth. The sharp hydrogen evolution at the deposition potential more negative than -1.1 V contributed to the decrease in nucleation density. Therefore, the nucleation density of the nickel nanoparticles can be manipulated by the deposition potential.